User's Manual

SPEEDLAN 9200 User Guide Part # 34357-MNL Rev.03
1-5
• Hardware AES 128-bit encryption for security between SPEEDLAN 9200
routers.
• You can recover lost IP addresses. (Use IP Recover in SPEEDManage.)
Note: Advanced Encryption Standard was adopted by the National Institute of
Standards and Technology in October of 2000. AES presents a new level in computer
networking security, especially important in wireless communications because wireless
circuits are easier to tap than their hard-wired counterparts.
AES is more difficult to crack than its predecessor Data Encryption Standard. These
routers use an AES 128-bit encryption key.
Encryption Note! A Web browser must support 128 bit encryption in order to be
used with the Configurator. For more information about AES, visit http://
www.nist.gov. This User Guide explains how encryption works with 9200 products in A.
Enabling Encryption Between SPEEDLAN 9200 Routers, page 4-4 and B. Enabling WEP
Security Between a SPEEDMesh-Enabled Client and SPEEDLAN 9200, page 4-5.
Priority Queuing
Despite having two physical interfaces, a SPEEDLAN 9200 router can experience
congestion. That is because the interfaces' bit rates are not matched. Specifically,
packets can ingress (enter) the Ethernet interface faster than they can egress (exit) the
wireless interface. If this occurs briefly, it is called short-term congestion, which can
cause increased packet delay and/or jitter. If congestion lasts too long, it can cause
packet discard ("loss"). Long-term congestion in a SPEEDLAN 9200 will typically only
occur when it receives excessive unthrottled UDP traffic at its Ethernet interface. TCP
traffic will self-throttle, typically experiencing only short-term congestion, if any.
A SPEEDLAN 9200 mitigates short-term congestion by providing priority egress
queuing at its wireless interfaces. With priority queuing, packets may be transmitted in a
different order than they were received. This allows favoring network management,
VoIP and SCADA, over SMTP, ftp, and NNTP (for example).
How does Priority Queuing work? The packets are prioritized into a hierarchy of
queues, based on class of traffic. The highest priority queue packets are serviced first.
When the highest queue is emptied, the next lower queue is serviced. The SPEEDLAN
9200 has four levels of priority queues.